You should probably auto-transport players to the Kitchen when a challenge is started, I didn't realize I was in the Box-less Factory and thought the object spawn rates just inexplicably got massively nerfed haha
When disks but not mouses have been unlocked, pressing 8 brings up the disk shop, but when mouses are unlocked, 8 brings up the mouse menu
Also, is there any way to exit challenges? I got stuck on Challenge 3 and had to re-enter and complete Challenge 1 just to get back to normal gameplay and grind more hammers